The photomechanical process includes a step of transforming a continuous-gradation original image into a halftone-dot image. In the process there has hitherto been applied a super-high-contrast image producing photographic technique that employs an infectious development.
The emulsion of a lithographic silver halide light-sensitive material for use in the infectious development is a high-silver-chloride-content (at least 50 mol %) silver chlorobromide emulsion comprising uniformly shaped silver halide grains having an average grain size of about 0.2 .mu.m with a narrow grain size distribution. The lithographic silver halide light-sensitive material of this type, when processed in an alkaline hydroquinone developer solution having a low sulfate ion concentration, i.e., a lith-type developer solution, can provide an image having a high contrast, a high sharpness and a high resolution. The lith-type developer solution, however, is unpreservable because it is subject to degradation by oxidation, so it is difficult to keep its developability constant when used continuously.
On the other hand, there is known a method capable of rapidly forming a high-contrast image without using such an unpreservable lith-type developer solution; for example, a method in which a tetrazolium salt or a hydrazine derivative is added to the light-sensitive material. According to this technique, contrasty images can be obtained even by using a well preservable developer solution for rapid processing.
However, the printing industry seeks better-quality printed matter producing techniques, since there is a strong demand for better-finished photographic image quality, particularly having still more improved image sharpness than ever before.
The hydrazine-derivative-containing silver halide photographic light-sensitive material has a problem of its own that after being processed, sandy fine black spots, so-called pepper fog occurs on its unexposed area. However, no drastic measures for solving this problem have yet been found to date.
Where a tetrazolium salt is used to harden the light-sensitive material, a developer solution for use in processing the light-sensitive material must contain a development restrainer, but the development restrainer is so hardly soluble in water that it requires the use of a large amount of an organic solvent, which causes an environmental problem at the time of processing and waste developer disposal problem.